[Rust] DOCS: Project status is too optimistic

[mryellow]

Expected behavior

The programs openvasd and scannerctl are usable, but might not support all features yet. The current openvasd implementation does not use and internal rust scanner yet, but still uses the c implementation of the openvas-scanner. Additionally depending on the configuration, an ospd-openvas instance is also needed.

Actual behavior

Errors in an unusable way. Does not report backend errors in API responses. #1744